Artificial intervertebral disc

Abstract

An artificial intervertebral disc comprising at least two individual disc units that create a single center of rotation within an intervertebral space. An artificial intervertebral disc including housing members including spaced inner surfaces facing each other and oppositely facing outer surfaces for engaging spaced apart intervertebral surfaces; self-adjusting bearing mechanisms operatively disposed between the inner surfaces for moving relative to the housing members to adjust and compensate for vertebral disc motion; and a flange formed on an outer surface of said housing members for aligning the disc in an intervertebral space. A method for posteriorly inserting an artificial disc assembly by inserting at least two artificial disc assemblies around a spine and into an intervertebral space.

1 . An artificial intervertebral disc comprising at least two individual disc units that create a single center of rotation within an intervertebral space.  
     
     
         2 . The disc according to  claim 1 , wherein each of said disc units includes housing members including spaced inner surfaces facing each other and oppositely facing outer surfaces for engaging spaced apart intervertebral surfaces; and 
 self-adjusting bearing means operatively disposed between said inner surfaces for moving relative to said housing members to adjust and compensate for vertebral disc motion.    
     
     
         3 . The disc according to  claim 2 , wherein each of said disc units further includes positioning ring means for controlling motion and position of said bearing means and for absorption of compressive loads.  
     
     
         4 . The disc according to  claim 3 , wherein said inner surfaces include at least one positioning ring means therein.  
     
     
         5 . The disc according to  claim 2 , wherein said housing members are constructed from a composition selected from the group consisting essentially of metals, ceramics, and plastics.  
     
     
         6 . The disc according to  claim 5 , wherein said housing members include an outer surface having a coating thereon.  
     
     
         7 . The disc according to  claim 6 , wherein said coating is selected from the group consisting essentially of TiN (Titanium Nitride), diamond, diamond-like materials, synthetic carbon-based materials, and chromium-based materials.  
     
     
         8 . The disc according to  claim 2 , wherein said bearing means is constructed from a composition selected from the group consisting essentially of metals, ceramics, and plastics.  
     
     
         9 . The disc according to  claim 3 , wherein said positioning ring means is made of a material selected from the group consisting essentially of rubber, silicone, polyurethane, urethane composites, plastics, polymers, and elastomers.  
     
     
         10 . The disc according to  claim 2 , wherein said housing members include at least one aperture for accommodating at least one bone screw.  
     
     
         11 . The disc according to  claim 2 , wherein said inner surfaces include at least one slot within each of said inner surfaces for seating said self-adjusting bearing means therein and allowing movement of said self-adjusting bearing means.  
     
     
         12 . The disc according to  claim 11 , wherein said slot includes outer walls defining the size of said slot and receiving means inside said slot, said receiving means for receiving and containing said bearing means therein.  
     
     
         13 . The disc according to  claim 12 , wherein said receiving means includes a seat portion integral within said housing.  
     
     
         14 . The disc according to  claim 11 , wherein said slot is in a shape selected from the group consisting essentially of a circle, an oval, and other round-sided shapes.  
     
     
         15 . The disc according to  claim 2 , wherein said housing members are constructed from a composition selected from the group consisting essentially of metals, ceramics, and plastics.  
     
     
         16 . The disc according to  claim 15 , wherein said housing members include an outer surface having a surface texture for accepting bone growth therein.  
     
     
         17 . The disc according to  claim 16 , wherein said surface texture is selected from the group consisting essentially of physically roughened, porous coated, and plasma coated surfaces.  
     
     
         18 . The disc according to  claim 12 , wherein said receiving means is a removable insert.  
     
     
         19 . The disc according to  claim 18 , wherein said insert includes outer walls defining a size of said insert and a seat for receiving and containing said bearing means therein.  
     
     
         20 . The disc according to  claim 19 , wherein said insert is in a shape selected from the group consisting essentially of a circle, an oval, and other round-sided shapes.  
     
     
         21 . The disc according to  claim 2 , further including load sharing means disposed between said inner surfaces and about at least a portion of said bearing means for sharing absorption of compressive loads with said bearing means while limiting the relative movement of said housing members.  
     
     
         22 . The disc according to  claim 21 , wherein said load sharing means includes at least one pad member disposed and retained between said inner surfaces of said housing members and having cushioning and elastic properties for countering and thereby self centering against forces caused by relative movement of said housing member while under compressive forces are applied to said outer surfaces of said housing members.  
     
     
         23 . The disc member according to  claim 22 , wherein said pad members are made from a composition selected from the group consisting essentially of polymers and elastomers.  
     
     
         24 . The disc member according to  claim 23 , wherein said pad members are made from a composition selected from the group consisting essentially of silicone, polyurethane, urethane composites, plastics, polymers, and elastomers.  
     
     
         25 . The disc according to  claim 22 , wherein said housing members includes seating means for seating said pad members between said inner surfaces.  
     
     
         26 . The disc according to  claim 25 , wherein said seating means includes at least one pocket recessed into said inner surface of said housing members for seating a portion of said pad member therein.  
     
     
         27 . The disc according to  claim 26 , further including adhering means for fixedly adhering said pad member within said pocket.  
     
     
         28 . The disc according to  claim 2 , further including self-centering means for automatically centering said self-adjusting bearing means within said housing members.  
     
     
         29 . The disc according to  claim 28 , wherein said self-centering means are load sharing means disposed between said inner surfaces and about at least a portion of said bearing means for sharing absorption of compressive loads with said bearing means while limiting the relative movement of said housing members and self-centering said bearing means.  
     
     
         30 . The disc according to  claim 2 , wherein said housing members include aligning means on an outer surface of said housing members for aligning said disc within the intervertebral space.  
     
     
         31 . The disc according to  claim 30 , wherein said aligning means is at least one flange.  
     
     
         32 . The implant according to  claim 2 , wherein said bearing surfaces are symmetrical around a center of rotation.  
     
     
         33 . The implant according to  claim 2 , wherein said bearing surfaces are non-symmetrical around the center of rotation.  
     
     
         34 . The implant according to  claim 1 , wherein said individual disc unit having at least some portion in contact with at least one other disc unit.  
     
     
         35 . The implant according to  claim 1 , wherein said individual disc unit having a portion engaging at least one other disc unit.  
     
     
         36 . A method for posteriorly inserting an artificial disc assembly by inserting at least two artificial disc assemblies around a spine and into an intervertebral space.  
     
     
         37 . The method according to  claim 36 , wherein said inserting step includes inserting each of the assemblies about a side of the spine into opposite sides of the intervertebral space.  
     
     
         38 . The method according to  claim 36 , wherein said inserting step includes aligning each of the assemblies within the intervertebral space to enable the two assemblies to function as a single assembly.  
     
     
         39 . The method according to  claim 38 , wherein said aligning step includes parallelly aligning the assemblies in the intervertebral space.  
     
     
         40 . The method according to  claim 38 , wherein said aligning step includes non-parallelly aligning the assemblies in the intervertebral space.  
     
     
         41 . The method according to  claim 38 , wherein said aligning step includes aligning the assemblies to create a single center of rotation.  
     
     
         42 . The method according to  claim 36 , wherein said inserting step includes posteriorly inserting at least two artificial disc assemblies around a spine and into an intervertebral space.  
     
     
         43 . The method according to  claim 42 , further including preparing the intervertebral space prior to insertion of the assemblies.  
     
     
         44 . The method according to  claim 43 , wherein said preparing step includes forming a space in the intervertebral space sufficient to house the assemblies.  
     
     
         45 . The method according to  claim 42 , wherein said preparing step includes forming at least one groove on a vertebral body located at the intervertebral space.  
     
     
         46 . The method according to  claim 42 , wherein said preparing step includes forming at least two grooves on a vertebral body located at the intervertebral space.  
     
     
         47 . The method according to  claim 45 , wherein said forming step includes parallelly forming at least two grooves on a vertebral body  
     
     
         48 . The method according to  claim 45 , wherein said forming step includes non-parallelly forming at least two grooves on a vertebral body  
     
     
         49 . The method according to  claim 45 , wherein said forming step includes forming at least two grooves on a vertebral body, whereby the grooves enable the assemblies to function as a single assembly.  
     
     
         50 . An artificial intervertebral disc comprising: 
 housing members including spaced inner surfaces facing each other and oppositely facing outer surfaces for engaging spaced apart intervertebral surfaces;    self-adjusting bearing means operatively disposed between said inner surfaces for moving relative to said housing members to adjust and compensate for vertebral disc motion; and    a flange formed on an outer surface of said housing members for aligning the disc in an intervertebral space.    
     
     
         51 . An artificial disc comprising at least two disc units that create a single center of rotation during at least one point in the range of motion of the bearing surfaces.  
     
     
         52 . An implant comprising at least two individual disc units that function as a single unit within the intervertebral space.  
     
     
         53 . An artificial disc comprising at least two individual disc units, said disc units having spherical bearing surfaces.